Matt Gilroy, the righty defenseman who rarely has played the left side in his five years on the blue line for Boston University and the Rangers, will get into his first game of the season tonight when the Maple Leafs come to the Garden, but on the left side.

That’s because Steve Eminger, the righty defenseman who rarely has played the left side in his seven-year NHL career, struggled on the left side in Buffalo and on the Island in the first two games and thus will shift back to the right.

Also, Michael Sauer, the righty defenseman who seemed far sturdier than Eminger in the opening two contests but simply cannot play the left side at all, is a healthy scratch for the home opener.

Coach John Tortorella was asked if it could be inferred that he believes Gilroy will do a better job on the left than Eminger did.

“Not really. I don’t know,” Tortorella said after yesterday’s practice. “I’m not crazy about any of it, putting a righty on the left side, either of ‘em, [but] Gilly had a good enough camp that he doesn’t need to be sat for a number or games here.

“That five-six position, we’re going to keep evaluating and see where we go with it. But I want to give Emmy a chance on the right side and see him there.”

The lack of a third lefty defenseman behind Marc Staal and Michael Del Zotto already has begun to take its toll. If Gilroy struggles, general manager Glen Sather likely will have to accelerate his pursuit of a veteran lefty.

If the price is not right, either in terms of the contract or the trade required to get one, it will then be important for Ryan McDonagh, the lefty rookie whom the organization had penciled into that third-pair spot, to develop as quickly as possible in the AHL.

Gilroy ($1.75 million), Eminger ($1.125M) and Sauer ($500,000) all need waivers in order to be assigned to the AHL, though Sauer would not need to go through re-entry to be recalled. McDonagh can move between the AHL and NHL without waivers or restriction.

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Tortorella talked about the demotion of Tim Kennedy, who was sent to the AHL on Wednesday in order to open a roster spot for Chris Drury’s return from injured reserve. The 24-year-old Kennedy, scratched from the opening two games, had cleared waivers last week.

“He’s a kid who has to play,” said Tortorella, whose early, perhaps over-the-top praise of Kennedy became muted as things evolved. “I think he had a good camp. It tailed a little bit, but it’s not going to help him sitting around here.

“When Dru came off, we had to do something and that was the decision. I had a couple of great conversations with him. He understands and he’s a great kid. We’ll see where we go as we move on here.”

It’s extremely unlikely that Kennedy, signed as a free agent in August after he was bought out by the Sabres following a $1 million salary arbitration award, ever will play a game for the Rangers. Earning $550,000, Kennedy would be available at half-price and half the cap on re-entry waivers should the Blueshirts attempt to recall him.

Though it was a surprise that Kennedy cleared waivers last week, Sather’s timing in exposing him to claim was perfect, coming as it did on the day clubs were required to submit their opening rosters to the league.

But teams will have seen their deficiencies and will have suffered injuries when and if the Rangers would attempt a recall. It is inconceivable that Kennedy, who recorded 26 points (10-16) as a rookie last year for Buffalo, would clear at $275,000.

“Sure,” said Tortorella, when asked if he were concerned that Kennedy would not be able to return.

It also would be a risk for the Rangers to expose themselves to $275,000 of dead cap space that, over the course of the year, could amount to up to $1 million in full season value around the trade deadline.

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In demoting Kennedy, the Rangers chose to keep 35-year-old center Todd White and his $2.375 million contract on the roster. White, who recorded 73 points two years ago with Atlanta before dropping to 26 last season, is currently no higher than sixth on the depth chart down the middle.

“He’s a great guy, we knew he was, he understands where he is with the team right now and he’s never complained once,” Tortorella said of White, who was still recovering from off-season surgery to repair a separated shoulder and was thus limited early in camp. “We’re not going to force-feed him, a lot of things can happen, [like] injuries and guys tailing off.

“He’s going to wait for his chance and I’m sure he’s going to seize it when he gets the opportunity.”

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Tonight’s game is first of three against Toronto in the Rangers’ next eight games. The Maple Leafs, who missed the playoffs last year, have opened 3-0 with regulation victories over Montreal, Ottawa and Pittsburgh.